| Parameter |
Value |
| Designation |
442P/McNaught |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2022-08-20T19:07:02.740800Z |
| Orbit solution date (soln_date, UTC) |
2024-07-07T00:42:22Z |
| Obs used |
452 |
| NEO |
- |
| M1 |
10.500 |
| K1 |
19.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-08-20.0000000 |
| e |
0.53159899 |
| q (au) |
2.328281 |
| a (au) |
4.970701 |
| i (deg) |
6.053247 |
| Ω (om, deg) |
32.033725 |
| ω (w, deg) |
310.972640 |
| M (ma, deg) |
229.993643 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.717 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.717 |
| n |
2.000 |
| gf |
0.993 |
| gb |
-0.900 |
| k |
0.999 |
| δ90 |
1.000 |
| Parameter |
Symbol |
Range |
Description |
| Absolute magnitude at 1 AU from Sun and Earth |
H0 |
-5 to 20 |
Intrinsic brightness of the comet |
| Photometric slope parameter |
n |
2 to 6 |
Rate of brightness change with heliocentric distance |
| Forward scattering asymmetry factor |
gf |
0.8 to 1 |
Degree of forward scattering |
| Backward scattering asymmetry factor |
gb |
-1 to -0.5 |
Degree of backward scattering |
| Partitioning coefficient |
k |
0.8 to 1 |
Ratio between forward/backward scattering contributions |
| Dust-to-gas brightness ratio |
δ90 |
1 to 10 |
Relative contribution of dust scattering to gas emission |
Reference: EPSC-DPS2025-160
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
10:12:06.79 |
+16:25:39.9 |
HIP 50040 |
14.09 |
| 2026-09-20 12:00 |
10:12:23.01 |
+16:24:18.0 |
HIP 50040 |
11.59 |
| 2026-09-21 00:00 |
10:12:39.19 |
+16:22:56.4 |
HIP 50040 |
10.21 |
| 2026-09-21 12:00 |
10:12:55.32 |
+16:21:35.1 |
HIP 50040 |
10.38 |
| 2026-09-22 00:00 |
10:13:11.41 |
+16:20:14.1 |
HIP 50040 |
12.02 |
| 2026-09-22 12:00 |
10:13:27.45 |
+16:18:53.4 |
HIP 50040 |
14.65 |
| 2026-09-23 00:00 |
10:13:43.44 |
+16:17:33.1 |
HIP 50175 |
14.84 |
| 2026-09-23 12:00 |
10:13:59.39 |
+16:16:13.1 |
HIP 50175 |
11.10 |
| 2026-09-24 00:00 |
10:14:15.28 |
+16:14:53.4 |
HIP 50175 |
7.69 |
| 2026-09-24 12:00 |
10:14:31.13 |
+16:13:34.0 |
HIP 50175 |
5.27 |
| 2026-09-25 00:00 |
10:14:46.94 |
+16:12:15.0 |
HIP 50175 |
5.37 |
| 2026-09-25 12:00 |
10:15:02.69 |
+16:10:56.3 |
HIP 50175 |
7.87 |
| 2026-09-26 00:00 |
10:15:18.39 |
+16:09:37.9 |
HIP 50175 |
11.27 |
| 2026-09-26 12:00 |
10:15:34.04 |
+16:08:19.9 |
HIP 50175 |
14.95 |
| 2026-09-27 00:00 |
10:15:49.64 |
+16:07:02.2 |
HIP 50323 |
12.29 |
| 2026-09-27 12:00 |
10:16:05.19 |
+16:05:44.9 |
HIP 50323 |
8.37 |
| 2026-09-28 00:00 |
10:16:20.69 |
+16:04:27.9 |
HIP 50323 |
4.51 |
| 2026-09-28 12:00 |
10:16:36.13 |
+16:03:11.3 |
HIP 50323 |
1.33 |
| 2026-09-29 00:00 |
10:16:51.52 |
+16:01:55.1 |
HIP 50323 |
3.72 |
| 2026-09-29 12:00 |
10:17:06.86 |
+16:00:39.2 |
HIP 50323 |
7.51 |
| 2026-09-30 00:00 |
10:17:22.14 |
+15:59:23.7 |
HIP 50323 |
11.35 |
| 2026-09-30 12:00 |
10:17:37.37 |
+15:58:08.5 |
HIP 50323 |
15.20 |
| 2026-10-01 00:00 |
10:17:52.54 |
+15:56:53.7 |
HIP 50323 |
19.05 |
| 2026-10-01 12:00 |
10:18:07.65 |
+15:55:39.4 |
HIP 50323 |
22.88 |
| 2026-10-02 00:00 |
10:18:22.71 |
+15:54:25.4 |
HIP 50560 |
20.94 |
| 2026-10-02 12:00 |
10:18:37.71 |
+15:53:11.7 |
HIP 50560 |
17.19 |
| 2026-10-03 00:00 |
10:18:52.65 |
+15:51:58.5 |
HIP 50560 |
13.49 |
| 2026-10-03 12:00 |
10:19:07.54 |
+15:50:45.7 |
HIP 50560 |
9.86 |
| 2026-10-04 00:00 |
10:19:22.36 |
+15:49:33.3 |
HIP 50560 |
6.44 |
| 2026-10-04 12:00 |
10:19:37.13 |
+15:48:21.3 |
HIP 50560 |
3.75 |
| 2026-10-05 00:00 |
10:19:51.83 |
+15:47:09.7 |
HIP 50560 |
3.84 |
| 2026-10-05 12:00 |
10:20:06.47 |
+15:45:58.5 |
HIP 50560 |
6.56 |
| 2026-10-06 00:00 |
10:20:21.05 |
+15:44:47.8 |
HIP 50560 |
9.94 |
| 2026-10-06 12:00 |
10:20:35.57 |
+15:43:37.4 |
HIP 50560 |
13.47 |
| 2026-10-07 00:00 |
10:20:50.02 |
+15:42:27.5 |
HIP 50560 |
17.05 |
| 2026-10-07 12:00 |
10:21:04.41 |
+15:41:18.1 |
HIP 50750 |
13.82 |
| 2026-10-08 00:00 |
10:21:18.73 |
+15:40:09.1 |
HIP 50750 |
10.59 |
| 2026-10-08 12:00 |
10:21:32.99 |
+15:39:00.5 |
HIP 50750 |
7.73 |
| 2026-10-09 00:00 |
10:21:47.18 |
+15:37:52.4 |
HIP 50750 |
5.81 |
| 2026-10-09 12:00 |
10:22:01.31 |
+15:36:44.7 |
HIP 50750 |
5.80 |
| 2026-10-10 00:00 |
10:22:15.36 |
+15:35:37.5 |
HIP 50750 |
7.69 |
| 2026-10-10 12:00 |
10:22:29.35 |
+15:34:30.7 |
HIP 50750 |
10.47 |
| 2026-10-11 00:00 |
10:22:43.27 |
+15:33:24.5 |
HIP 50829 |
12.73 |